/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.iotdb.flink.tsfile;

import org.apache.flink.api.common.io.FileInputFormat;
import org.apache.flink.api.common.typeinfo.TypeInformation;
import org.apache.flink.api.java.typeutils.ResultTypeQueryable;
import org.apache.flink.api.java.typeutils.TypeExtractor;
import org.apache.flink.configuration.Configuration;
import org.apache.flink.core.fs.FileInputSplit;
import org.apache.flink.core.fs.Path;
import org.apache.flink.runtime.util.HadoopUtils;
import org.apache.flink.util.FlinkRuntimeException;
import org.apache.iotdb.flink.tsfile.util.TSFileConfigUtil;
import org.apache.iotdb.hadoop.fileSystem.HDFSInput;
import org.apache.iotdb.tsfile.common.conf.TSFileConfig;
import org.apache.iotdb.tsfile.read.ReadOnlyTsFile;
import org.apache.iotdb.tsfile.read.TsFileSequenceReader;
import org.apache.iotdb.tsfile.read.common.RowRecord;
import org.apache.iotdb.tsfile.read.expression.QueryExpression;
import org.apache.iotdb.tsfile.read.query.dataset.QueryDataSet;
import org.apache.iotdb.tsfile.read.reader.LocalTsFileInput;
import org.apache.iotdb.tsfile.read.reader.TsFileInput;

import javax.annotation.Nullable;
import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;
import java.nio.file.Paths;
import java.util.Optional;

/**
 * Input format that reads TsFiles. Users need to provide a {@link RowRecordParser} used to parse the raw data read
 * from TsFiles into the type T.
 *
 * @param <T> The output type of this input format.
 */
public class TsFileInputFormat<T> extends FileInputFormat<T> implements ResultTypeQueryable<T> {

	private final QueryExpression expression;
	private final RowRecordParser<T> parser;
	@Nullable
	private final TSFileConfig config;

	private transient org.apache.hadoop.conf.Configuration hadoopConf = null;
	private transient ReadOnlyTsFile readTsFile = null;
	private transient QueryDataSet queryDataSet = null;

	public TsFileInputFormat(
			@Nullable String path,
			QueryExpression expression,
			RowRecordParser<T> parser,
			@Nullable TSFileConfig config) {
		super(path != null ? new Path(path) : null);
		this.expression = expression;
		this.parser = parser;
		this.config = config;
	}

	public TsFileInputFormat(@Nullable String path, QueryExpression expression, RowRecordParser<T> parser) {
		this(path, expression, parser, null);
	}

	public TsFileInputFormat(QueryExpression expression, RowRecordParser<T> parser) {
		this(null, expression, parser, null);
	}

	@Override
	public void configure(Configuration flinkConfiguration) {
		super.configure(flinkConfiguration);
		hadoopConf = HadoopUtils.getHadoopConfiguration(flinkConfiguration);
	}

	@Override
	public void open(FileInputSplit split) throws IOException {
		super.open(split);
		if (config != null) {
			TSFileConfigUtil.setGlobalTSFileConfig(config);
		}
		TsFileInput in;
		try {
			if (currentSplit.getPath().getFileSystem().isDistributedFS()) {
				// HDFS
				in = new HDFSInput(new org.apache.hadoop.fs.Path(new URI(currentSplit.getPath().getPath())),
					hadoopConf);
			} else {
				// Local File System
				in = new LocalTsFileInput(Paths.get(currentSplit.getPath().toUri()));
			}
		} catch (URISyntaxException e) {
			throw new FlinkRuntimeException(e);
		}
		try (TsFileSequenceReader reader = new TsFileSequenceReader(in)) {
			readTsFile = new ReadOnlyTsFile(reader);
			queryDataSet = readTsFile.query(
					// The query method call will change the content of the param query expression,
					// the original query expression should not be passed to the query method as it may
					// be used several times.
					QueryExpression.create(expression.getSelectedSeries(), expression.getExpression()),
					currentSplit.getStart(),
					currentSplit.getStart() + currentSplit.getLength());
		}
	}

	@Override
	public void close() throws IOException {
		super.close();
		if (readTsFile != null) {
			readTsFile.close();
			readTsFile = null;
		}
	}

	@Override
	public boolean reachedEnd() throws IOException {
		return !queryDataSet.hasNext();
	}

	@Override
	public T nextRecord(T t) throws IOException {
		RowRecord rowRecord = queryDataSet.next();
		return parser.parse(rowRecord, t);
	}

	@Override
	public boolean supportsMultiPaths() {
		return true;
	}

	public QueryExpression getExpression() {
		return expression;
	}

	public RowRecordParser<T> getParser() {
		return parser;
	}

	public Optional<TSFileConfig> getConfig() {
		return Optional.ofNullable(config);
	}

	@Override
	public TypeInformation<T> getProducedType() {
		if (this.getParser() instanceof ResultTypeQueryable) {
			return ((ResultTypeQueryable) this.getParser()).getProducedType();
		} else {
			return TypeExtractor.createTypeInfo(
				RowRecordParser.class,
				this.getParser().getClass(), 0, null, null);
		}
	}
}
